IEC 60825-1:2014

IEC 60825-1 ®
Edition 3.0 2014-05
INTERNATIONAL
STANDARD
NORME
INTERNATIONALE
colour
inside
GROUP SAFETY PUBLICATION
PUBLICATION GROUPÉE DE SÉCURITÉ
Safety of laser products –
Part 1: Equipment classification and requirements

Sécurité des appareils à laser –
Partie 1: Classification des matériels et exigences

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IEC 60825-1 ®
Edition 3.0 2014-05
INTERNATIONAL
STANDARD
NORME
INTERNATIONALE
colour
inside
GROUP SAFETY PUBLICATION
PUBLICATION GROUPÉE DE SÉCURITÉ

Safety of laser products –
Part 1: Equipment classification and requirements

Sécurité des appareils à laser –

Partie 1: Classification des matériels et exigences

INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
COMMISSION
ELECTROTECHNIQUE
PRICE CODE
INTERNATIONALE
CODE PRIX XE
ICS 13.110; 31.260 ISBN 978-2-8322-1499-2

 IEC 2017
INTERNATIONAL ELECTROTECHNICAL COMMISSION
____________
IEC 60825-1
Edition 3.0  2014-05
SAFETY OF LASER PRODUCTS –
Part 1: Equipment classification and requirements

INTERPRETATION SHEET 1
This interpretation sheet has been prepared by IEC technical committee 76: Optical radiation
safety and laser equipment.
The text of this interpretation sheet is based on the following documents:
FDIS Report on voting
76/587/FDIS 76/593/RVD
Full information on the voting for the approval of this interpretation sheet can be found in the
report on voting indicated in the above table.

IMPORTANT – The 'colour inside' logo on the cover page of this publication indicates
that it contains colours which are considered to be useful for the correct
understanding of its contents. Users should therefore print this document using a
colour printer.
___________
Subclause 4.3 Classification rules
This subclause is clarified by the following:
Introduction
For some complex extended sources or irregular temporal emissions, the application of the
rules of subclause 4.3 may require clarification because of changes from IEC 60825-1:2007.
NOTE 1 For the purpose of this interpretation sheet, the abbreviation “AE” is used for “accessible emission”.
NOTE 2 The clarifications also apply in an equivalent way to MPE analysis, i.e. for Annex A.
ICS 13.110; 31.260
– 2 – IEC 60825-1:2014/ISH1:2017
 IEC 2017
1 Subclause 4.3 b) Radiation of multiple wavelengths
See IEC 60825-1:2014/ISH2.
2 Subclause 4.3 c) Radiation from extended sources
When using the default (simplified) evaluation method (subclause 5.4.2) for wavelengths
≥ 400 nm and < 1 400 nm, the angle of acceptance may be limited to 100 mrad for
determining the accessible emission to be compared against the accessible emission limit,
except in the wavelength range 400 nm to 600 nm for durations longer than 100 s where the
circular-cone angle of acceptance is not limited. When evaluating the emissions for
comparison to the Class 3B AELs, the angle of acceptance is not limited.
3 Subclause 4.3 d) Non-uniform, non-circular or multiple apparent sources
In subclause 4.3 d), for comparison with the thermal retinal limits, the requirement to vary the
angle of acceptance in each dimension might appear to contradict the labelling in Figure 1
and Figure 2 of subclause 5.4.3 where the field stop is labelled as circular.
Interpretation
A circular field stop is applicable for circularly symmetric images of the apparent source and
for this case is consistent with the procedure given in subclause 4.3 d). For images of the
apparent source that are not circularly symmetric, the simple example below clarifies the
application of subclause 4.3 d).
A circular field stop with an angular subtense equal to α is, however, applicable for non-
max
circularly symmetric profiles if the analysis performed according to subclause 4.3 d), following
variation of the angle of acceptance in each dimension, results in a solution which is equal to
α in both dimensions.
max
As a general principle, for whatever emission duration t the AEL is determined (such as the
pulse duration, the pulse group duration or the time base for averaging of the power), the
same emission duration t is also used to calculate α (t).
max
The following example demonstrates the method described in subclause 4.3 d) to analyse
irregular or complex images of a source. It is noted that the example is equivalent to the
second part of the example (“Additional Remarks”; 6 mrad spacing instead of 3 mrad) B.9.1 of
IEC TR 60825-14:2004 (however, for 6 mrad element spacing, the result in terms of which
grouping is critical was not correct). The source is a diode array (Figure 1). The task is to
determine the applicable AEL that limits the AE for Class 2. Each diode contributes a partial
accessible emission AE of 1 mW that passes through a 7 mm aperture stop at the distance
where the analysis is performed (i.e. a total power of 20 mW passes through the aperture
stop), and the emission is continuous wave. The analysis requires determination of the most
restrictive (maximum) ratio of AE over AEL by variation of the angle of acceptance in position
and size to achieve different fields of view.

 IEC 2017
α = γ
x1 x1
6 mrad
α = γ
x2 x2
2,8 mrad
α = γ
α = γ
y2 y2
y1 y1
2,2 mrad
IEC
Figure 1 – Image of a source pattern for the example of 20 emitters. Two possible
groupings are defined by the respective angle of acceptance γ and γ
x y
The analysis of a sub-group of sources is associated with a certain value of α for that group,
and a certain accessible emission associated with that sub-group. For instance α of a single
element equals (1,5 mrad + 2,2 mrad)/2 = 1,85 mrad so that the AEL = 1,23 mW. The
applicable AE = 1 mW and AE/AEL = 1 mW/1,23 mW = 0,8. For a vertical two-element group,
as shown in the figure with γ and γ , α = (2,8 + 2,2)/2 = 2,5 mrad so that AEL = 1,66 mW;
x1 y1
AE = 2 × 1 mW = 2 mW and AE/AEL = 1,2, which is more restrictive than AE/AEL for only one
element. For one row of 10 diodes α = (1,5 + 56,2)/2 = 28,9 mrad, AEL = 19,2 mW, the AE =
10 × 1 mW = 10 mW and AE/AEL = 0,5. Analysis of all possible groupings shows that the
vertical two-element group has the maximum AE/AEL and therefore is the solution of the
analysis. This means that the AEL of Class 2 is exceeded by a factor 1,2. Note that only a
portion of the power of 20 mW that passes through the 7 mm aperture stop is considered as
the AE (2 mW; as partial power within the angle of acceptance that is associated to the part of
the image with the maximum ratio of AE/AEL) that is compared against the AEL. The entire
array represents the highest ratio of AE/AEL in cases where the element spacing is
sufficiently close, e.g. when the contributions of extra elements to the AE are not dominated
by the increased AEL due to the larger subtended angle.
For pulsed emission, for the determination of α according to the above method (4.3 d)) where
the ratio of AE to AEL is maximized, requirement 3) of 4.3 f) is not applied, i.e. the AEL is
single
not reduced by C . Due to the dependence of α on emission duration t, the analysis of the
5 max
image of the apparent source may result in different values of α and of the partial accessible
emission, depending which emission duration is analysed for the requirements of 4.3 f). For
example, for emission durations shorter than 625 µs (α = 5 mrad), the maximum partial
max
array to consider in the image analysis is a vertical two element group.
Ref.: Classification of extended source products according to IEC 60825-1, K. Schulmeister,
ILSC 2015 Proceedings Paper, p 271 – 280; Download:
https://www.filesanywhere.com/fs/v.aspx?v=8b70698a595e75bcaa69
4 Subclause 4.3 f) 3) determination of α
For an analysis of pulsed emission, α , which is a function of time α (t), limits both the
max max
value of α for the determination of C (α) as well as the angle of acceptance γ for the
determination of the accessible emission (see 4.3 c) and d)) and Clause 3 of this
interpretation sheet; in this process, α (t) is determined for the same emission duration t
max
that is used to determine AEL(t) (i.e. the pulse duration or the pulse group duration for
α is
4.3 f) 3) and the averaging duration for 4.3 f) 2), respectively). However, the parameter
also used in subclause 4.3 f) 3) in the criteria which C is applied. For these criteria, the
parameter α is not limited in the same way as for the determination of C according to 4.3 d).
For the criterion “Unless α > 100 mrad”, the angular subtense of the apparent source α is not
restricted by α . For non-uniform (oblong, rectangular, or linear) sources, the inequality
max
needs to be satisfied by both angular d
...